The present invention is directed to devices that are used for rodent control, the rodents being gophers, moles or other burrowing types of animals. This invention is more particularly directed to an apparatus which dispenses a measured portion of poison directly into a gopher burrow or runway.
The need for probing devices which are able to deposit bait or poison into rodent burrows has long been recognized. The general goal of all of these devices is to locate and penetrate the gopher burrow with a minimal amount of disruption, deposit a load of bait, and remove the tool leaving the burrow intact. The deposited bait should, at least by appearance, present an appetizing treat for the unsuspecting gophers, such that the grain has not been broken into a powder or mixed with dirt. Because a network of rodent burrows can be quite extensive, with a large number of rodents, it is desirable for the application device to store multiple doses of bait, which may be individually dispensed in a single measured dose.
A problem encountered by these devices is that because the bait is dispensed through openings in a hollow probe, the openings can become plugged with dirt. As the probe is used to locate and penetrate gopher burrows, the probe tip is repeatedly pushed through the ground, leaving dirt deposited in any openings in the probe. The known devices have attempted to solve this problem through a number of different mechanisms. For example, U.S. Pat. No. 1,890,391, issued in 1932, employs a port located near the tip of the probe which opens by rotating the device. U.S. Pat. No. 3,771,474 discloses a device which uses a plunger with a plug for blocking the discharge of poison from the barrel of the device until the plunger is retracted. When the plunger is raised, the poison is discharged through the tip of the probe. The device disclosed in U.S. Pat. No. 4,413,440 attempts to solve the plugging problem by dispensing the poison through a lateral outlet opening immediately above the lower terminal end of the tube. Poison is released through the lateral outlet by actuating a rotary valve. The device disclosed in U.S. Pat. No. 4,614,160 dispenses poison through the tip, which is plugged with a penetrator during efforts to locate and penetrate the gopher burrow. The common feature of the cited devices and the other known probing and dispensing devices is that the probe portion of each device, from which the bait is dispensed, is round in shape. The round shape of the probe limits the means by which bait or other materials may be dispensed from a device.
Despite the efforts to solve the problem of dirt plugging in the probe, the known devices continue to have a variety of problems, including: (1) dirt plugging of the probe; (2) plugging of the probe with bait; (3) failure to dispense the proper dose of bait; (4) grinding the poison grain too finely or mixing the grain with dirt, resulting in an ineffective bait; or (5) being too complicated resulting in a high initial investment and/or high maintenance expenses and/or difficulties in cleaning and field stripping. A gopher probe is needed which does not have these problems.
The present invention is directed to a gopher probe which meets the need identified above.
The disclosed apparatus comprises an elongated four-sided hollow shaft. The hollow shaft has a handle end and a dispensing end. Three of the four sides of the hollow shaft taper at the dispensing end to form a shaft tip for penetrating and probing the ground surface. A pusher bar is slideably attached to one side of the hollow shaft, such that the pusher bar slides relative to the long axis of the shaft. The pusher bar has two ends, the operator end coinciding with the handle end of the hollow shaft, and the sealing end, coinciding with the dispensing end. The sealing end forms a closure at the shaft tip. At the operator end, the pusher bar may be connected to a thumb plate, which may be activated by the user""s thumb or palm acting on a pushing surface.
Two of the four sides, the straight sides, are at facing opposite sides of the hollow shaft. At the shaft tip, each straight side has a xe2x80x9cV-shapedxe2x80x9d pointed end. The other two sides of the hollow shaft comprise, at facing opposite sides, the bait tank side and the pusher bar side. The bait tank side is so named because it is the side of the hollow shaft on which the bait tank is attached. The pusher bar side is so named because it is the side to which the pusher bar is slideably attached. The pusher bar side may have a groove adapted to receive groove guides attached to the pusher bar, which slideably attach the pusher bar to the pusher bar side. The bait tank side terminates at the shaft tip, the bait tank side having an angled-end which is complimentary to the adjacent angle of one leg of the xe2x80x9cVxe2x80x9d formed by each of the straight sides, the angled-end forming a seal on one side of the shaft tip. The pusher bar side terminates above the shaft tip. The fourth side of the shaft tip is formed by the sealing end of the pusher bar which extends below the pusher bar side.
The sealing end of the pusher bar is angled, with an angle complimentary to the adjacent angle of the leg of the xe2x80x9cVxe2x80x9d formed by the two straight sides, opposite the leg of the xe2x80x9cVxe2x80x9d sealed by the angled-end of the bait tank side. As the pusher bar slides with respect to the hollow shaft, the sealing end either seals the pusher bar side of the shaft tip in a first position, or unseals the pusher bar side of the shaft tip in a second position.
The handle end of the hollow shaft may have a tee-shaped handle to assist the user in probing efforts. A bait tank for storage of poison or other material to be dispensed attaches to the hollow shaft between the handle end and dispensing end, the bait tank having a lower end facing the shaft tip and an upper end facing the handle end. The bait tank has a sealable hole for loading the bait tank with the gopher bait or other material to be dispensed. In one embodiment, the bait tank has a calibrated orifice, located adjacent to the upper end, the calibrated orifice facing upwards toward the handle end. The calibrated orifice forms the entry into the measured dose reservoir. The measured dose reservoir connects to the shaft opening, allowing the contents of the measured dose reservoir to enter into the hollow shaft and fall through the hollow shaft to the shaft tip. A measured dose of gopher bait is placed at the shaft tip by first lifting the device so that bait within the bait tank is placed above the calibrated opening, then lowering the device, thereby filling the measured dose reservoir, the dose of bait thereafter falling to the shaft tip.
During probing efforts, the sealing end of the pusher bar is in the raised, or closed position so that the four tapered sides of the shaft tip are aligned forming a point. Once the gopher burrow is located and the probe in place, the sealing end is placed in the lowered position by pushing down on the thumb plate. Pushing down on the thumb plate causes the pusher bar and the sealing end to slide in a downward direction relative to the hollow shaft, so that the sealing end extends downward past the other sides of the tapered shaft tip thereby opening the shaft tip. The measured dose of bait within the hollow shaft falls through the opening into the gopher burrow. The sealing end is then closed by raising the pusher bar by pulling up on the thumb plate or allowing the pusher bar to rise to its normal biased position, and the shaft removed from the gopher burrow. Following this procedure, the tool may be used repeatedly until the bait tank is empty.